In today's technological world, there is an increasing need for membrane switches that can be mounted on cathode ray tubes (CRT's). An ever increasing amount of software is becoming available that requires the user to answer questions by pressing appropriate areas of a CRT equipped with a membrane switch.
Membrane switches were initially developed for use in such items as calculators, computer keyboards, cash registers, games and the like. In manufacturing these items, the membrane switches are essential to the operation of the device. Housings for the items had to be developed to encase the switches.
A membrane switch used on a CRT, however, is an optional piece of equipment. The CRT can be fully operational without the membrane switch. The switch must be designed to fit an existing object. Mounting the switches to CRT's therefore presents unique problems.
Mounting is a particular problem with switches made from successive layers of essentially transparent film. It is essential that the film be held securely in place against the firm surface of the CRT. It is desirable that the means for mounting the switch not block any of the operable area of the switch. Furthermore, the method of mounting should permit realignment of the switch should the switch become distorted during use and easy replacement should the switch become damaged.
Heretofore, membrane switches for CRT's have been profiled to the shape of a CRT. The methods used for mounting these switches include the use of adhesive gaskets to adhere the switch to the face of the CRT and the use of brackets to surround a portion, or all, of the outer perimeter of the switch and a portion of the face of the CRT. There are problems associated with the above methods, particularly in aligning and replacement of the switch.
The disclosed invention solves the problems associated with mounting membrane switches on CRT's. An essential part of the means for mounting, integral with the switch itself, eliminates the use of gaskets and brackets. The means for mounting is comprised of a plurality of extensions of film along the perimeter of at least one layer of the film and a plurality of coupled fastening assemblies. The assemblies are comprised of two separable parts, the inner surfaces of which have a very large number of closely spaced hooking elements of the hook and loop type that engage with each other when the two parts are pressed together. One outer surface of the assembly is adhered to the film extensions and the second outer surface is fastened to the sides of the CRT. The fastening assemblies hold the switch securely to the CRT without blocking any of the face of the CRT, and at the same time permit easy realignment if the film becomes distorted during use. Furthermore, the switch can be removed and replaced with a minimum of effort.